Study on improvement of the generator end fixed structure and optimization of pretightening process

Abstract

To address recurring issues identified during comprehensive maintenance of a specific generator model—particularly the loosening of ring lead fixing structures at the generator ends, along with the detachment of felt and insulation wear—a detailed investigation was conducted. This study focused on analyzing the root causes of these problems and developing targeted improvement strategies. Taking the ring lead fixing structure as the research object, the investigation explored enhancements to the fixing structure and optimization of the bolt pretightening process. By comparing the fixing structure of faulty units with that of fault-free units and considering practical field conditions, a solution involving an increased cleat wrapping angle was proposed. The effectiveness of this improved design was verified through testing. Furthermore, the interaction of adjacent bolts during the stretching of single-head bolt stretchers was investigated for the bolt pre-tightening process. In view of the bolt pretightening process, the study explored the interaction between adjacent bolts when utilizing single-head bolt tensioners was studied, and experiments using multi-head synchronous hydraulic tensioners were conducted to evaluate their pretightening performance. The results revealed the pretightening behavior of multi-head systems, demonstrating their superior efficiency compared to single-head methods. These findings provide a robust foundation for applying such systems in industrial settings. This study aims to resolve technical challenges related to the ring lead fixing structure and the bolt pretightening process, ultimately ensuring the safe and stable operation of the generator.